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Gao Y, Kaushik S, Philip EJ, Li Z, Qin Y, Liu YP, Zhang WL, Su YL, Chen X, Weng H, Kharzeev DE, Liu MK, Qi J. Chiral terahertz wave emission from the Weyl semimetal TaAs. Nat Commun 2020; 11:720. [PMID: 32024831 PMCID: PMC7002692 DOI: 10.1038/s41467-020-14463-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 01/08/2020] [Indexed: 11/23/2022] Open
Abstract
Weyl semimetals host chiral fermions with distinct chiralities and spin textures. Optical excitations involving those chiral fermions can induce exotic carrier responses, and in turn lead to novel optical phenomena. Here, we discover strong coherent terahertz emission from Weyl semimetal TaAs, which is demonstrated as a unique broadband source of the chiral terahertz wave. The polarization control of the THz emission is achieved by tuning photoexcitation of ultrafast photocurrents via the photogalvanic effect. In the near-infrared regime, the photon-energy dependent nonthermal current due to the predominant circular photogalvanic effect can be attributed to the radical change of the band velocities when the chiral Weyl fermions are excited during selective optical transitions between the tilted anisotropic Weyl cones and the massive bulk bands. Our findings provide a design concept for creating chiral photon sources using quantum materials and open up new opportunities for developing ultrafast opto-electronics using Weyl physics.
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Affiliation(s)
- Y Gao
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - S Kaushik
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - E J Philip
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Z Li
- State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, Beijing Key Laboratory of Quantum Devices, Peking University, Beijing, 100871, China
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Y Qin
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
- Institute of Electronic and Information Engineering, University of Electronic Science and Technology of China, Dongguan, 523808, China
| | - Y P Liu
- Institute of Modern Physics, Fudan University, Shanghai, 200433, China
| | - W L Zhang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - Y L Su
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China
| | - X Chen
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA
| | - H Weng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - D E Kharzeev
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA.
- Department of Physics, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA.
- RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, NY, 11973-5000, USA.
| | - M K Liu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794, USA.
| | - J Qi
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, China.
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Buividovich PV, Chernodub MN, Kharzeev DE, Kalaydzhyan T, Luschevskaya EV, Polikarpov MI. Magnetic-field-induced insulator-conductor transition in SU(2) quenched lattice gauge theory. Phys Rev Lett 2010; 105:132001. [PMID: 21230764 DOI: 10.1103/physrevlett.105.132001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Indexed: 05/30/2023]
Abstract
We study the correlator of two vector currents in quenched SU(2) lattice gauge theory with a chirally invariant lattice Dirac operator with a constant external magnetic field. It is found that in the confinement phase the correlator of the components of the current parallel to the magnetic field decays much slower than in the absence of a magnetic field, while for other components the correlation length slightly decreases. We apply the maximal entropy method to extract the corresponding spectral function. In the limit of zero frequency this spectral function yields the electric conductivity of quenched theory. We find that in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field.
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